The present invention relates to an apparatus for operating a valve element according to the preamble of claim 1.
Generally, electromagnetics are employed for operating hydraulic multi-port valves. With these, coil currents of a few hundred milliamperes are necessary at a supply voltage of, for example, 12 volts to produce the necessary driving force of typically 100 Newtons.
With the addition of an environment posing an explosive danger (for example the individual current circuits in an underground coal mine) it is however very desirable to keep the necessary electrical power as small as possible for safety. As a rule, there are approximately eight functions to control at an installation in a coal project according to each design. Since individual networks are not available for any desired power, a network must be installed to serve approximately five installations. Under such circumstances, it is already contemplated that not all of the valves will be controlled at once.